Tri-color cathode ray image reproducing tube



Jan. 8, 1957 J. M. LAFFERTY 2,777,083

TRI-COLOR CATHODE RAY IMAGE REPRODUCING TUBE Filed Feb. 5. 1952. 4Sheets-Sheet 1 Fig.3.

y/n d I N Inventor".

James M. Laffertg,

9c b5 $14 M 0 His Attorney.

TRI-COLOR CATHODE RAY IMAGE REPRODUCING TUBE Filed Feb. 5. 1952 Jan. 8,1957 J. M. LAFFERTY 4 Sheets-Sheet 2 Fi g4. O

@ QD on FigJO.

Inventor: Jam es M. Laffertg, by Z 4 7 His Attorney.

J. M. LAFFERTY 2,777,088

TRI-COLOR CATHODE RAY IMAGE REPRODUCING TUBE Jan. 8 1957 4 Sheets-Sheet4 Filed Feb. 5, 1952 Figll.

FiglZ.

Inventor: James M. Laffevtg, b5 )QJ a. 7 7

His Attorney.

REPRODUCIN G TUBE James M. Lafierty, Schenectady, N, Y., assignortoGeneral Electric Company, a corp ra ion of New Yo k Application February5, 1952, Serial No. 269,978

Claims. Cl. 315-21 The present invention relates to a tri-color,cathoderay image reproducing tube that is particularly Well suited foruse in a color television receiving system.

M Pa ti ularly, the invention relates to a trircolor, cathode-ray imagereproducing tube of the reflecting type, and to a new and improvedtri-color image reproducing eleetro'de structure for such tube, andthernethod of making such structure.v i i A tri-color cathode-ray imagereproducing tube of the reflecting-type comprises generally a vacuumsealed envelope having an electron gun disposed therein, and a first,"apertured, image reproducing electrode member supportedctherein whichhas a plurality of symmetrically arranged different coloredphosphorescent materials se The first apertured elec cured to one of itssurfaces. trode member is supported in the envelope with the phos-'phorescent material coated surfacethereof adapted to be viewed throughthe face of the tube,and with the electron gun disposed on theside-thereof opposite the phosphorescent material coated surface in amanner such that the electron beam emitted by the electron gun must passhrou h e pe u in th m m r e r mp n ing on the different coloredphosphorescent material. Disposed between the phosphorescent materialcoated surface of the electrode member and the tube face is a second,transparent, electrically conductive, reflecting electrode mem-. her towhich is applied a reflecting electric potential that coacts with anelectric potential applied to the apertured electrode member to producea retarding electric field between the two members that causes theelectron beam passing through the apertures in the first electrode mem;her to be reflected back, and to impinge on a desired coloredphosphorescent material. Thus, as the electron beam emitted by theelectron gun is caused to sweep out a desired image by properlypositioned vertical and horizontal electron beam displacing meansdisposed adjacent the electron beam path, the image thereby reproducedcan be caused to have a desired color by controlling the particularcolor phosphorescent material upon which the reflected electron beamimpinges. The particular color phosphorescent material excited by thereflected electron v fi i tgdlstates Patent ice effects as arcingbetween the two spaced-apart different potential electrode members;vibration of the first aperturcd electrode member (which results invarying the spacing between the two different potential members andthereby affects the point of return of the reflected electron imagereproducing tube that is particularly suitable'for use in a colortelevision receiving system.

Another object of the invention is to provide an image reproducing tubeof the above type which is relatively simple and cheap to construct, andwherein activation of the desired color sequences can be obtainedwithout requiring use of complicated circuitry or mechanical structure.

Still another object of the invention is to provide an improvedstructure for supporting in spaced-apart relation, twlo'elements of animage reproducing tube which are maintained at diflerent electricpotentials.

A further object of the invention is to provide an improved supportingframe construction for a cathode-ray tube image reproducing electrodemember that includes a vibration damping means for reducing to a minimumany tendency of the electrode member to vibrate.

A still further object of the invention is to provide a new and improvedmethod of forming apertured members from relatively thin sheet material,which method is particularly suitable for producing thin aperturedelectrode members designed for use in cathode-ray image reproducingtubes in that the members thus produced can reduce to a minimum anyshading'efi'ect that the member might have on the'intensity of anelectron beam as the beam passes through the apertures thereof.

One feature of the present invention is the provision of an imagereproducing electrode for a cathode-ray tube Which comprises aplanar'backing member having a plurality of concentrically arrangedarcuate rows of phosphorescent material secured to one of its surfaces.In

a particular embodiment of the image reproducing elecnode, the planarbacking member is electrically, co n-v ducti've and has a plurality ofconcentrically arranged arcuate rows of spaced-apart apertures formedtherein,

1 and a plurality of concentrically and symmetrically arbear will ofcourse be determined by the point at which the electron beam impinges onthe first apertured electrode member, and this in turnis determined by anumber of factors including the spacing of the two electrode mern hers,their relative electric potentials, and the a gleolj incidence oftheelectron beam with respect/to the plane of the apertured electrodemember. factors can be controlled in one manner or another so that adesired color image can be reproduced by a catty de- 73v imag rep d i tuon t d in; he above described manner; however, difiiculties have been eneren ed with e p n ly known. tubes of thisttype which have prohibitedtheir. widestpead adoption. in! cluded among thesedifiiculties are theprovision of a suff ciently satisfactory, cheap and simple methodofeolor control, n t e ab lity t el minate or reduce. s ch ranged 'arcuaterows of dilferent color producing phosphorescent materials are securedto one surface thereof intermediate ,the rows of apertures. In thisembodiment of the image reproducing electrode, the position of theconcentric rows of apertures and phosphorescent material are,established by varying length radii having thesame centerpoint,and'rotated through respective angular dis tan'ces determined by thedimensions of the imagereproducing area of the electrode.

Another feature of the invention is the provisionof an electrodestructure for a cathode-ray tube whichcomprises a first electricallyconductive electrode member maintained at a predetermined electricpotential, and a second electrically con'ductivemeiriber spaced from thev first member, and maintained at an electric potential dif- All of theabove ferent than the electric potential of the first member, the firstand second members being maintainedin the abovedescribed spaced-apartrelation by a plurality of spacer elements having a relatively highresistivity to the flowof e1ectric urrent' i c A further featuretof theinvention; is the provision of an electrode structure for a cathode-raytube which comprises a supporting frame, a relatively thin planar'conductive riember adapted to be disposed in the electron beam of a cathode.ray tube and having the outer edges' thereof secured to the frame in adrumhead fashion, and

vibration damping means cooperating with therelatively thin electrodemember to reduce vibrations thereof.

A still further feature of the invention is the provision of anelectrode for a cathode-ray image reproducing tube which comprises arelatively thin sheet of material having a plurality of aperturestherein, the opposing edges of the relatively thin sheet of materialdefining desired ones of the apertures being formed at predeterminedangles with respect to the surface of the member.

In its preferred form, the invention provides a new and improved,reflecting-type, tri-color, cathode-ray image reproducing tubeincorporating all of the above set forth novel features of construction.

Other objects, features, and many of the attendant'advantages of thisinvention will be appreciated more readily as the same becomes morefully understood by reference to the following detailed description,when considered in connection with the accompanying drawings, whereinlike parts in each of the several figures are identified by the samereference character, and wherein: Fig. 1 is a sectional view of areflecting type, .tri-color, cathoderay image reproducing tubeconstructed in accordance with the invention; Fig. 2 is adiagrammaticview of the physical relationship of a pair of spaced-apartelectrode members comprising the image reproducing electrode structureof the cathode-ray tube shown in Fig. l, and illustrates the path ofmovement of an electron projected into the space between the two,electrode I members; Fig. 3 is a diagrammatic sketch illustrating thepreferred geometrical relationship between the image reproducingelectrode member and the electron gun, of the reflecting type tri-colortube illustrated in Fig. 1; Fig. 4 is a plan view'of an apertured,tri-color, image reproducing electrode member and of the supportingframe therefor showing the manner in which the electrode member issupported; Fig. 5 is an enlarged plan view of a fragmentary portion ofthe electrode member shown in Fig. 4; Fig.6 is a diagrammatic viewillustrating the geometrical relationship between "the various aperturesof the apertured electrode member shown in Fig. 4, and illustrating themanner in which each one of one particular series of concentric rows ofapertures is located on the apertured electrode member; Fig. 7 is aserie's'of views illustrating the various steps in forming the aperturesin the apertured electrode member shown in Fig. 4; Fig. 81s a series offragmentary sectional views showing the various kinds of apertures thatcan be formed in the apertured electrode member of Fig. 4; Fig. 9 is afragmentary section View illustrating the manner in which the twospaced-apart electrode members of I the tube shown in Fig. 1, andillustrated diagrammatically in Fig.

has an electron gun, indicated at 14, disposed therein.

The electrons emitted by electron gun 14 are focused into a relativelysharp beam by a focusing coil 15 arranged around a portion of conicalneck portion 13, and the beam of electrons thus formed are caused toscan over the area of a reflecting type, tri-color, image reproducingelectrode structure, indicated at 16, by a set of vertical deflectioncoils 17 and horizontal deflection coils 18, in a manner such that theelectron beam appears to be emitted from a point source of origin 19.

The reflecting type, tri-color, image reproducing electrode structure 16is in manyrespects similar to the electrode structure of the tri-color,reflecting type, image reproducing tube disclosed in my United Statespatent application Serial No. 208,875, Color Television Apparatus andMethod, filed February 1, 1951, now Patent No. 2,741,720, but differstherefrom in a manner to be pointed out hereinafter. The electrodestructure 16 includes a first planar backing member 21 which, as is bestseen in Fig. 2 of the drawing, has a plurality of apertures 22 formedtherein, and a plurality of difierent colored phosphorescent materialssecured thereto, comprising a blue light emitting phosphorescentmaterial 23, a green light emitting phosphorescent material 24, and ared light emitting phosphorescent material 25, which are symmetricallyarranged intermediate the apertures. Spaced from and parallel to thefirst electrode member 21 is a second, transparent, electricallyconductive reflecting electrode member 26 disposed between firstelectrode member 21 and the transparent face portion 12 of the tube, andmaintained at some electric potential Vc, different from an electricpotentiol V0 applied to first aper tured electrode member 21. Thepotential V0 is the potential difference existing between first,apertured electrode member 21 and the electron gun cathode, assumed tobe at zero reference potential. It is also the potential applied to theaccelerating electrode of the electron gun" so that it is therefore thepotential which acts upon the electron beam emitted by the electron guncathode to accelerate the electrons in the beam toward the member 21. Asthe electron beam is scanned over the area of member 21, this electronbeam is intermittently disposed over one of the apertures 22, in whichevent the electron 2, are maintained in spacedapart relationship; Fig.10 is a side view of the supporting frame for the electrode member shownin Fig. 4; Fig. 11 is a side view of a mounting block adapted to besecured to the supporting frame shown in 10, and comprising a part ofthe vibration damping means incorporated into the tube structureillustrated in Fig. 1 to reduce vibration of the thin image reproducingelectrode member thereof; and

Fig. 12 is a plan view of the mounting block shown in Fig. 11.

beam passes through the aperture, and enters into the area betweenelectrode members 21 and 26. Because the potential Vc of reflectingelectrode member 26 is considerably less than the potential V0 ofelectrode member 21, the two potentials coact to produce a uniformretarding electric field throughout the area between the two members'The electrons passing through the apertures in first electrode member 21then, enter this retarding field, are reflected thereby so that theydescribe a more or less parabolic path, indicated at 27, and impingeupon one of the different colored phosphorescent materials 2325. By thisarrangement, with the perpendicular distance d between the electrodemembers held at a fixed value, the electron beam entering the retardingfield may strike, say the green light emitting phosphorescent material24 in the manner shown for one set of values of V0 and V0. .If theretarding field is' then increased in magnitude by decreasing thereflector voltage Vc for example, the electron beam follows a slightlydifferent trajectory and strikes the blue light emitting phosphorescentmaterial23. Similarly, by decreasing the magnitude of the retardingfield, the electron beam may be made to strike the red light emittingphosphorescent material 25. With a fixed value of a retarding field, andby proper distribution of the phosphorescent materials and the velope 11for enclosing the various elements of the tube v apertures on theelectrode member 21, then, it is possible to excite only a desired colorphosphorescent material as the electron beam is scanned back and forthover electrode member 21 in tracing out an image. Hence, the image to bedisplayed on the electrode member 21 can be reproduced in either red,green, or blue by utilization of the proper apertured electrodememberreflector Geometrical layout of apertured electrode member Inorder to determine the voltagesrequired, the geometrical layout'ofapertured electrode, member 21, and

other pertinent characteristics of the electrode structurediagrammatically illustrated in Fig. 2, it is necessary to determine'the various mathematical relations that exist between'the electronmotion, the applied voltages and the tube geometry, and, particularly,the geometry of the reflecting, tri -color electrode structure withrespect tothe point source of electrons 19. For the purpose ofconvenience in this discussion, the plane of apertured electrode member21 in Fig. 2, is arranged to define the X-axis of a set of Cartesiancoordinates, and a perpendicular to the plane of electrode member 21defines the Y-axis, with the origin. of the coordinates located in thecenter: of any one vof'the apertures 22 in member 21. With the reflectorelectrode member 26 spaced parallel to apertured electrode member 21,and at a fixed distance d from it, the voltages V and Vc produce auniform retarding field in the enclosed area which is given by theexpression: r i i The, mathematical expression of the force acting onan, electron when the same enters the retarding field E; can bedeveloped from the classical physical expression of Newtons second lawof motion:

where f is the force acting on the electron-to retard the same, m is themass of the electron, and a is the acceleration of the electron. Fromelementary electron physics it is known that force acting on an electronhaving a charge (-e) in an electric, field E, is given by the expressionf=(e)E, and; that the acceleration of an electron, or for that matterany body in motion, is equal to to time Thus, Equation 2 may beexpressed in the following manner:

Fo mexpression for the trajectory of an electron beam which enters theretarding field E at an angle. of incidence m measured with respect ,toatnormal to the plane of le tro m m r 21, a be ive ro -Equa i n 3 bytransposing Equation 3 to separate the two variables dy and dz. Theexpression thus obtained may be solved by integrating dv between thelimits of v and 110 cos a (where v is the y component of the velocity atthe variable time t, v0 is the initial velocityof the electron uponenteringthc retarding field at time i=0, and-v0 cos a is the componentof the velocity in the direction of the field. at time 21:0), and byintegrating dt between the limits of .0 and any variabletime t after theelectron has entered theretarding field E. Thisstep results in anexpression:

to 005 or V sults; in:

eE i i t in Equation 5, transposing, and integrating the termscontaining y between thelimits 0 and y, and the terms containing 2between the limits (land 23, the following ex- "Bysubstituting the.identity tpressilonmay be obtained:

1/ i fdy=v cos a results in;

Y refe g o 2 t is adi v ppa en thattht component of v in the directionof the x-a-xis (vii) is givenby: I

Since the distance x, the displacement of the electron along the x-axisfrom the point at which it enters the field E to the point at which itimpinges on the apertured x=tvo sin a From a consideration of electronPhysics, it can, be shown that the kinetic energy acquired by anelectron at the time it reaches any one of the apertures 22 in eloctrode member 21, and therefore the kinetic energy of an electron whenit passes through the origin of the co.- ordinate system underconsideration, is given by:

mv V e (:1 1)

Solving Equation 11 to obtain an expression for the velocity .of theelectron when the same passes through the origin, in terms of theelectric potential applied to elec trode member 21 results in:

Substituting Expression 12in Equation 10 and simplify ing, results in:

4d sin a ("13) 2d sin 2a lf the distance from the apertured electrodemember 21 to the zero Potential plane in the retarding field, measuredparallel to the y-axis, is denoted do, then and, Equation 14 may beexpressed in the following manner:

7 ConsideringEquation 16, it is readily apparent that if the angle ofincidence of the electron beam is 45, the displacement of the beam (S)is exactly twice the distance (do) between the apertured electrodemember 21, and the zero potential plane. If the angle of incidence ismade greater or less than 45 the displacement drops ofi. Consequently atcz=45, S is a maximum, and is equal to 2:10. If this value of S isidentified as S0, Equation 16 may be written: I

S=S sin 20c (17) Referring now to Fig. 3 of the drawing, the plane ABCErepresents the image reproducing area of the apertured electrode member21, and the point 0 represents the point source 19 of the electron beamemitted from the electron gun of the reflecting type, tri-color tubearrangement illustrated in Fig. 1. From a consideration of Fig. 3, it isobvious that as the beam .scans over the image reproducing area ABCEof'electrode member 21 along a straight line from left to right or rightto left in tracing out an image in the usual manner the angle ofincidence or is constantly changing. Consequently, this means that ifthe distance d, and the ratio Y vo are held constant, the displacementof the beam (S) is constantly changing in accordance with Equation 14.Thus, it can be appreciated that with straight line scanning across theimage reproducing area ABCE, it would be impossible to excite a singledistinct color over the entire area if the arrangement of apertures anddifferent colored phosphorescent material were symmetrically arranged.Because it is desirable for obvious reasons to have the rows of spacedapart apertures 22, and different colored phosphorescent materialsymmetrically arranged on electrode member 21, it is essential to workout some method of controlling the particular color phosphorescentmaterial excited by the reflected electron beam, independently of thechanges in a due to vertical and horizontal scanning. This could beaccomplished'by using a curved reflecting electrode member 26, bymodulating the reflecting electrode member voltage Vc, by a combinationof both, or by some other means; however, it appears much simpler tokeep a constant, and with a fixed value of let S vary with or accordingto Equation 14. When op- 'erated in this manner, a pattern can bemadeout of apertures, and different colored phosphorescent materials in sucha way that it is possible to excite only a single desired color whilethe area ABCE is being scanned. Then, by changing the reflector voltageVc, or by some other method of color control, it is possible toselectively excite any desired one of the plurality of different coloredphosphorescent materials 23, 24, or 25 at any instant during thescanning cycle of the electron beam as the same sweeps out an image onelectrode member 21.

In order to accomplish the above result, it is necessary to lay out thepattern. of apertures and difierent colored phosphorescent materials onelectrode member 2.1 in the form of concentrically arranged rows, eachof which follows an arcuate contour line of constant angle of incidenceover the image reproducing area ABCE of the electrode member. This isdone by drawing a perpendicular from the point 0 (which represents thepoint source of the electron beam 19) to a plane containing the planeABCE (and therefore the plane of the electrode member 21). The point atwhich this perpendicular intersects the above-referred to plane,identified as O, constitutes a common center point for varying lengthradii utilized in tracing out the plurality of concentrically arrangedarcuate rows, such as LMN by rotation of a particular length radius,such as R, through an angular distance determined by the width of theimage reproducing area ABCEof the electrode member 21. When an electronenters the retarding field through an aperture along one of these arcs,for example the arc LMN, it makes a constant angle of incidence a withthe apertured electrode member 21 at any point along the length of thearc. It will therefore return to, and impinge upon the electrode member21 at a constant distance S above the point on the are through which itenters the retarding field, measured along a radial line passing through0' as a center, and the point where the beam enters the retarding field(assuming d and to be held constant.

Considering now the triangle formed by three intersecting linescomprising the perpendicular distance between the point source ofelectron beam 0 and the common center point 0 (identified as h), theradius R of any particular arcuate row of apertures or phosphorescentmaterial such as LMN, and the straight line connecting the free end of Rand D (identified as Z for the purpose of convenience). ThenSubstituting the values for sin a and cosine a in the wellknowntrigonometric identity (sin 211:2 sin a cos a), and simplifying, it canbe shown that 2Rh Ra+h Substituting the value of sin 2a obtained inExpression 18 in Equation 17 and simplifying, results in:

sin 2a= ranged, arcuate rows of apertures can be laid out over theimage-reproducing area ABCE of the electrode member 21 with a series ofsymmetrically and concentrically arranged ditferent colored arcuate rowsof phosphorescent material disposed intermediate each row of apertureswhereby the electron beam upon passing through any one of the aperturescan be reflected back, and made to impinge upon a desired colorphosphorescent material. The preferred construction of electrode member21 utilizing the above set forth structural features, is illustrated inFigs. 4 and 5, wherein it is seen that apertures 22 are formed inconcentrically arranged arcuate rows having a common center point in amanner such that the apertures in difierent rows are aligned along astraight line radiating outwardly from the common center point. Disposedintermediate the arcuate rows of apertures are the continuous, unbroken,arcuate different colored lines of phosphorescent material 23, 24, and25 which are likewise concentrically arranged with respect to the rowsof apertures 22, and a common center point.

With regard now to the spacing between each of the arcuate rows ofapertures 22, it has been shown that the maximum displacement of thebeam (So) occurs when a=, and that the beam displacement (S) drops offenemas for values of or on either side of 45. Hence, it can be seen thatas the electron beam is scanned between the upper and lower limits ofits vertical sweep, the value of uyaries, for the smallest angle ofincidence a which the beam makes with the apertured electrode member 21will be at the point P in Fig. 3 of the drawings, and the largest angleof incidence will occur at the points A and B. Consequently, thedisplacement S varies in accordance with Equation 19, and it istherefore necessary that the spacing between the arcuate rows ofapertures 23 likewise vary. By proper design of the apertured electrodemember 21, it is possible to make the spacing between the arcuate rowsof apertures 23 at F approximately equal to the spacing between the rowsof apertures 23 at A andB, and thereby simplify somewhat theconstruction of the apertured electrode member. This can be accomplishedby making the value of the beam displacement S at point F, approximatelyequal to the value of S at points A and B.

In order to determine the value of the beam displacement S at points F,A and B, it is first desirable to detera mine the limits on the valuesof the least angle of incidence ML, and the greatest angle of incidencem that the electron beam makes with the plane of the electrode member21. To do this, there are certain inherent characteristics of thereflecting type image reproducing electrode structure described herein,which should be considered in arriving at the values of the maximum andminimumangles of incidence 06g and an. The most im portant of' thesecharacteristics is the focusing action of the retarding fieldE in theplane of incidence of the electron beam. A mathematical expression forthis phenomena may be obtained by difierentiating Equation 14 withrespect to a, and results in the following expression:

It can be shown from elementary trigonometry that electrons traveling ina beam with uniform velocity and diverging from the axis of the beamwith an angle doc, assumed to be extremely small, will, after travelinga distance So, be displaced transversely a distance Soda. From thischaracteristic, when considered in connection with Equation 20, it canbe seen that, if 2 cos Zais less than 1, then a focusing action occurs,and, if the quantity 2 cos 2a is greater than 1, a defocusing actionoccurs. Consequently, it can be shown that the greatest focusing actionwill occur when the angle of incidence c is 45, and that a defocusingaction will occur when or is less than 30, or greater than 60. Thus, ifone is to take advantage of the inherent focusing action of thereflecting type image reproducing electrode structure, the limits of thevertical scan should be established so that an equals or is greater than30, and m is equal to or less than 60. 7 This limi- =2S cos 2a (20)tation 0n the scanning angle is nottoo severe, in view angle ofincidence aL from a consideration of the focusing action of retardingfield on the beam, as set forth in the preceding paragraph, the leastradius R1. can be computed for the first arcuate row of aperturespassing through point F on electrode member 21. In making suchcomputation, it would be convenient to obtain an expression whichdiscloses more readily the relationship of a particular radius R, andits associated angle of incidence 0:. For this purpose, consider theare, shown in- Fig. 3,

of radius OA', and drawn from A to A where it inter-- sects the verticalcenter line 06 passing through the center of theimage-reproducing areaABCE. The pointsO, 0'

I0 and A, then define a rightvtriangle (illustrated in Fig. 6 of thedrawings) having one of the right angle legs thereof equal to h, and theremaining right angle leg equal to the maximum radius Rg=O'A'-, Theangle ozL=a1 then, is the least angle of incidence that the electronbeam makes with the apertured electrode member, and occurs at the pointF; and the angle cz=ot1v is the greatest angle of incidence that theelectron beam makes with respect to electrode member 21, and occurs atpoints A and B. The values of Rg=RN,. the maximum radius from point 0'which defines an arc passing through points A and B, and the radiusRr,=R1, the least radius from point 0' which defines an arc passingthrough the point F, can be found by solving Equation 19 for the ratioThis can be done by transposing Equation 19 and simplifying, and resultsin a quadratic expression that can be, solved by substitution in thequadratic formula to produce the following. equation:

trated in Fig. 6 along with Equation 21, the following expressionsrelating the values of a; and d1. can be ob- Aft'er values for the ratioand for the dimensions of the image reproducing area have been selected,the value ofRr. (or R1 since Rg=R1). can be computed from Equation 22.Having obtained the value R: for the radius of the first row of arcuateapertures then, from a consideration of Figs. 3-6 of the drawings, itcan be seen that an electron which enters the retarding fieldbetweenelectrode members 21 and 26 at any point along the length of thearcuate row of apertures defined by radius R1, will return to theapertured electrode member 21, and impinge thereon at a distance S1 fromthe aperture through which it centered, measured along a radial linewhich passes through 0', and the aperture. The distance S1 may becomputed from Equation 19 by substituting the value of R1 for R, and byadding R1 S1, the value of the length of the radius R2 of the nextmost,concentrically arranged, arcuate row of apertures in a series of suchrows of apertures to be formed in the electrode member 21, can bedetermined. By substi tution of value R2 for R in Equation 19, the valueof S2 can be obtained, and by adding R2 and S2, the value of the lengthof the radius R3 of the next following arcuate row of apertures in theseries in question, can be obtained. From the two preceding operations,it is believed apparent that a general recurrence formula for computingthe radius of any desired one of the arcuate rows of aperturescomprising a particular series of such apertures, may be obtained, andhas the following form:

With Equations 24 and 25, it is possible to lay out a series of arcuaterows of apertures which are arcs of concentric 1 1 circles havingvarying length radii, and a common center point at O.

With the arrangement so far described, if the ratio were kept constant,electrons which enter the retarding field B through the nth row ofapertures in electrode member would pass back out of the retarding fieldthrough the (nth-i-l) row of apertures without impinging on theelectrode member. However, by modulating the ratio with the receivedcolor switching information, the electrons entering through the nth rowof apertures can be made to impinge upon any desired one of thedifferent colored rows of phosphorescent material which are disposedadjacent to the apertures,

In order to obtain satisfactory image resolution, it is desirable thatabout 75% of the image reproducing area of electrode member 21 beoccupied by the colored phosphorescent materials 23, 24, and 25, andapproximately 25% of the remaining image reproducing area of theelectrode member be occupied by apertures. Consequently, it is necessaryto interlace additional series of arcuate concentrically arranged rowsof apertures, i. e., a number of series, each one comparable to theseries of rows of apertures having radii R1, R2, R3, between the seriesof apertures, R1, R2 Rn where R1t=Rg. The exact number of additionalrows of apertures to be interlaced between the arcuate row of apertureshaving radius R1 and the arcuate row of apertures having a radius of R2,will depend primarily on the width of the individual apertures, and thevalue of So. Because the positioning of the first arcuate row ofapertures in each additional series of apertures to be interlacedbetween the arcuate rows of apertures ofthe first series (i. e., theparticular arcuate row of apertures of the additional series that willbe positioned intermediate the arcuate rows of apertures having radii oflength R1 and R2 res'pectively), will automatically determine theposition of the remaining arcuate rows of apertures in each additionalseries by virtue of Equation 24, it is desirable to position theadditional arcuate rows of apertures inserted between the rows' ofapertures having radius R1 and R2, in such a way that the remainingarcuate rows of apertures in each series will be uniformly spacedwithout abrupt discontinuities in the spacing. To do this, the mostsatisfactory method used to date, has een to determine the position ofthe first arcuate row of apertures in each series by means of Newtonsinterpolation formula:

where it takes on the successive values m m m m m is the total number ofadditional series of arcuate rows of apertures to be interlaced betweenthe series R1, R2, R3 and the deltas are the tabular difierences betweencorresponding rows of apertures in the series R1, R2, R3 Rn. The generalrecurrence formula set forth in Equation 24 may then be used with thevalues of Ri-j-k computed from Equation 26 to obtain the positions ofthe remaining arcuate rows of apertures in each additional series.

Method of construction of apertured image reproducing electrode memberHaving determined the desired geometrical layout of the concentricallyarranged arcuate rows of apertures and different colored lines ofphosphorescent material for the image reproducing apertured electrodemember 21, the next step to be accomplished is the construction of themember. Referring now to Fig. 7 of the drawings, the method steps of theoperation to be carried out in forming the desired concentricallyarranged arcuate rows of apertures in the member 21 is disclosed.Apertured electrode member 21 is constructed from a flat, relativelybroad sheet of electrically conductive material 31 shown in Fig. 7a, inwhich the desired apertures are formed by etching, punching, or somesimilar operation. Because the most practical way of forming the desiredapertures is to etch the same in the sheet of material 31, the materialshould also be easily etched. Therefore, one material out of which theapertured electrode member 21 can be formed is copper; however, the mostsatisfactory results to date have been accomplished with the use of acopper, beryllium and cobalt alloy identified as Trodaloy, and disclosedin any one of United States Patents 1,847,929; 2,225,339; 2,226,284; or2,283,675. This material is particularly well suited for use inconstructing apertured electrode member 21 because of its many desirablecharacteristics which include a high electrical conductivity, arelatively high Youngs modulus of elasticity, a high service temperatureand the ability to be readily etched.

In carrying out the operation of forming apertures, the particularmethod used is disclosed in United States Patent No. 2,437,228, andincludes coating a light sensitive emulsion 32 over one of the surfacesof the sheet of material 31, in the manner shown in Fig. 7a. A mask 33having a plurality of opaque areas 34 where it is desired that aperturesbe formed in the sheet of material 31, is then deposited over the lightsensitive emulsion 32, and the areas of the emulsion not covered byopaque portions 34 are exposed to a source of illumination 35 asillustrated in Fig. 7b. Mask 33 is then removed, and the emulsion-coatedsheet of material 31 subjected to treatment with a developing fluid thatremoves only those areas of the light sensitive emulsion not exposed tothe source of illumination 35, in the manner shown in Fig. 7c. The areasof the light sensitive emulsion 32 that were exposed to source ofillumination 35 are unafiected by the developing fluid, and remain onthe sheet of backing material 31 to form masks over those portions ofthe sheet of backing material where it is desired that no apertures beformed.

Having completed the above steps on one side of the sheet of material21, the sheet of material is then turned over, and the identicaloperations performed on the opposite side of the sheet of material asindicated in Figs. 711, 7c and 7). In the operation carried out on theopposite side of the sheet of material 31, however, the opaque areas 34of the mask 33 are offset a predetermined amount in a predetermineddirection from the center of the first bores 36 in the first treatedside of the sheet of material, in the manner shown in Fig. 7e. Uponexposure of the light sensitive emulsion 32 to source of light 35, andremoval of the unexposed portions of the light sensitive emulsion 32 bya developing fluid, the sheet of material 31 has the form shown in Fig.7f. Thereafter the sheet of material is subjected to a suitable etchingbath which acts upon the portions of the sheet of material not coveredby mask 32 to form a set of first bores 36 in one side thereof, and aset of second bores 37 in the remaining side thereof, in the mannershown in Fig. 7g. Subsequent to this operation, the masking material 32is removed, and results in the blank apertured electrode member 21'shownin Fig. 711.

Because of the offset given to masking material 32, each one of the setof second bores 37 is offset a predetermined amount from itscorresponding first bore 36, and the resulting aperture 22 formed by thejuncture 13 9f e o bor asthe id hereo (d fined by the thin ed s of theet f e a ma essome p d erm n d a le ith' sp e t t e surf of he et, ofmaterial. Asis best seeninFigs. 8a, 8b and 8c, the a u that e c espnding ba es and 3 are fset, generally determines the angle that thesides of the a u e formed y hei ncturef of b es makes it r spect to thesurface of the sheet of material, and therefore the angle of incidencethat a beamof electrons passing through the aperture, can make withrespect to the plane of the sheet of material 31 in order that themaximum cross-sectional area ofthe aperture be exposed to the electronbeam whereby no reduction in. the intensity of the beam. will occur dueto shading efiects of the edges of the apertures, as the beam. passesthrough the aperture. t

A better appreciation of the results accomplished by forming angularapertures22 in the electrode member 21-: can be obtained from aninspection of Figs. 3, 8 and 9 of the drawings; Considering the" pointP, in the center of image reproducing area ABCE of apertured electrodemember 21, it can be appreciated :that the angle of incidence that anelectron beam makes with the plane of the electrode member 21 at thispoint is some value intermediate the least and greatest angles ofincidence, for example 45. The apertures 23 formed in the vicinity of.point P therefore should be constructed as shown in Fig. 8a so thatsubstantially the full intensity of an electron beam, indicated at 38,will pass. through the aperture with no shading effects. If, instead offorming the aperture 23 is electrode member 21 at point P in the mannershown in Fig. 8a of the drawing, the aperture was formed with the sidesthereof substantially vertical to, the surface of thesheet of material31, in the manner shown in Fig. 8d of the drawings, the path of theelectronv beam 38. would be shaded almost. entirely by the sidesof theapertures which are approximately equal in width to the thickness ofsheet of material 31. This could be corrected byfenlarging the apertures22 in electrode. However, wider aperturedimensions would of coursedisrupt the beam displacement calculations. aswell as destroy theresolution of an image reproduced on the member, and are thereforeimpractical. Thus, it is not only desirable but almost necessary thatthe sides of the aperture form some predetermined angle with respect tothe plane of electrode member-21, and, in the manner described withrelation to Fig 7, this can be most satise ous unbroken arcuate linethat extends over an angular distance determined by the dimensions ofthe image reproducing, area of the electrode member. In securing thephosphorescent material to the blank apertured member 21, the aperturedmember first has a vehicle, for example, nitrocellulose or linseed. oil,printed thereon, by means of either a letter press or a lithographingop-. eration. The vehicle is.printed in the form of a first series ofconcentrically arranged, arcuate lines located on apertured electrodemember 21 in the position of the. concentrically arranged arcuatelinesof one color phos-. phorescent material, for example the greenlight emitting phosphorescent material 24. Thereafter, the particularcolor phosphorescent material to be located in the position of the firstprinted series of lines is dusted over the entire surface of theapertured electrode member, and adheres to those portions of theelectrode member on which the vehicle is printed. The excessphosphorescent material is then blown off in any suitable manner. Thisoperationthen completes depositing of one of the-colored arr-77,089

1'4 phosphorescent materials, on: the electrode. member 21.

Electrode member. 21. is then moved slightly, and again has a. vehicleprinted thereon, along a series of con.- eentricallyarranged lines.spaced? slightly fromv the lines previously printed, and located'in theposition of the con.- centr-ically arranged arcuate lines of a second,different colored phosphorescent material, for example the, blue light:emitting phosphorescent material 23. The second colored phosphorescentmaterial is then. dusted over the entire screen, and adheres only to theportions of the screen having the exposed vehicle printed thereon. Theexcess'phosphorescent materialwhichv does not fall upon the exposed,vehicle is then blown off, and. will. include any phosphorescent.material which might have fallen upon the first deposited phosphorescentmaterial.

-After securing the second. colored phosphorescent material to theapertured electrode member, the member is againmoved slightly andtheentire procedure repeatedto deposit the third. coloredphosphorescentmaterial along the series of concentricallyarrangedarcuate. lines which it is to occupy, in accordance with thecalculations set forth in the section covering the geometrical layout ofthe member. While the particular order in which the different colored.lines are depositedon the electrode member 21 is not too important, isis desirable that the strongest phosphorescent material i. e., thephosphorescent material that is. capable of producing the greatestamount oflight) be deposited first, and the Weakest phosphorescentmaterial be deposited last.

Because of the fact that the diiferent color phosphorescent material.are deposited. on the electrode member 21 in continuous arcuate lines,all areas upon which electrons might; impinge should they drift,sidewise a small amount in'returning tothe electrode member, are coveredq with a phosphorescent material. Thus, such electrons are Mechanicalconstruction of tube After construction of the apertured, tri-colored,image reproducing electrode, member 21 in the manner describedin thepreceding section, the component parts of the tube structure are readyto be assembled together to form the completed article. One of the firststeps in assembling the completed tube is to. support the aperturedtri-colored ele trode member 21 in spaced-apart, parallel relationshipwith the electrically conductive, transparent, reflecting electrodemember 26. If desired, this step may be accomplished in a subassemblyoperation prior to securing the reflecting type electrode structureformed thereby in the tube envelope, in order to simplify constructionand speed up manufacture of the completed tube. Prior to this step,however, the apertured tri-colored member 21 is mounted in a drumheadfashion on a substantially annular supporting frame 41, the constructionof which is described more fully hereinafter, and the mounted apertured,tri-colored member then supported in spaced-apart, parallel relationshipwith the transparent reflecting member 26. Transparent electricallyconductive reflecting electrode member 26 preferably comprises a plateof electrically conductive glass available on the marketcommerciallythrough any one of a number of glass manufacturing concerns,such as Corning Glass Works, Pitts,- burgh Plate Glass Company, andothers, and as is best shown in Fig. 9, consists essentially ofa pane ofplate glass having a relatively thin, electrically conductive,transparent coating 42 on at least one surface thereof. The twoelectrode members are supported in spaced-apart parallel relationshipwith conductively coated surface of reflecting electrode member 26adjacent aperture elec-.

trode member 21, and are maintained at two diflercnt electricpotentials, the potential of the reflecting electrode member 26 beingless than the potential of the apertured tri-colored electrode member 21so that a retarding electric fieldexists in the area between the twomembers.

In order to support the two electrode members 21 and 26 in spaced-apart,parallel relationship, the electrode members are rigidly secured withinthe jaws of an electrically conductive U-shaped clamp 43, by means of aplurality of spacer elements 44 having a relatively high resistivity tothe flow of electric current. The spacer elements 44 preferably comprisea plurality of electrically conductive lead silicate glass blocks havinga substantially rectangular cross-section, and having the surfacethereof hydrogen-treated so as to produce a very thin conducting layeron the outside surface. The conducting layer thus produced has a surfaceresistance in the order of some 800 megohms square or more, so that eachspacer element acts as a very high resistance, voltage divider betweenthe electrode members 21 and 26. As is best shown in Fig. 9 of thedrawings, transparent reflecting electrode member 26 has theelectrically conductive surface 42 thereof formed around the edges ofthe side opposite electrode member 21 so as to provide a contact surfacefor a spacer element 44 disposed between the electrode member 26 and onejaw of U-shaped clamp 43. Another spacer element 44 is disposed betweenmember 26 and aperture tri-colored electrode member 21, with thesupporting frame 41 of electrode member 26 engaging the remaining jaw ofU-shaped clamp 43. The entire arrangement is held in rigidly assembledrelation by means of an adjusting screw 45 in the end of one of the jawsof U-shaped clamp 43, which coacts with the end of one of the spacerelements 44 to place each of the elements 44, reflecting electrodemember 42, and the supporting frame 41 of apertured electrode member 21under compression between the jaws of U-shaped clamp 43. If desired, aball bearing point support may be provided between the supporting frame41 and the end of the jaw of U-shaped clamp 43, and a relatively softgasket material 46 may be disposed between the end of adjusting screw 45and the end of the spacer element 44 with which it comes in contact, toprevent breakage of the spacer element. In all, there are a total offour structures'similar to that shown in Fig. 9 spaced about theperiphery of the electrode members 21 and 26, one at eachcorner, torigidly hold the two members in spaced-apart, parallel relationship.

Because of the above-described construction of the spacer elements 44,each of the elements acts as a high resistance, voltage divider betweenthe electrode members 21 and 26. As previously stated a potentialgradient exists between the two members by reason of the application ofthe potential V to the conductive coating 42 of reflecting electrodemember 26 by means of a resilient contact arm 47 having a V-shapedcontact 48 engaging the rectangular corner of the edge of the electrodemember, and the application of an electric potential Vo (which isgreater than V0) applied to electrode member 21, supporting frame 41,and existing on U-shaped clamp 43. Due to the fact the spacer elements44 are electrically conductive, this potential gradient is evenlydistributed over the length of the spacer elements in the mannerindicated in Fig. 9 so that arcing between the electrode members and thespacers is substantially prevented, yet because the spacer elements havea sufficiently high resistivity to the flow of electric current,sufiicient leakage current does not flow across spacer elements toseriously affect the operation of the tube.

Referring now to Figs. 4 and of the drawings, the construction of thesupporting frame 41 for apertured, tri-colored electrode member 21, isillustrated. The supporting frame 41 comprises a substantially annularbody portion 5'1, having a generally rectangular cross-section, and aplurality of internally threaded bolt holes 52 spaced about itsperiphery. Adapted to be secured to the body portion 51 of supportingframe 41 is a face plate portion 53 which may comprise a single integralpiece, or a plurality of individual pieces, of strip material shaped tocomplementarily fit around the annular surface of body portion 51. Theapertured tri-colored electrode member 21, which has a plurality of boltholes 54 formed around its periphery axis best shown in Fig. 4 of thedrawings, is secured over body portion 51 with the bolt holes 54 thereinaligned over the bolt holes 52 in body portion 51, and the face plateportion 53 is secured thereover with the bolt-receiving aperturesthereof also aligned with the bolt holes 52 and 54. The entire assemblyis then secured together by means of a plurality of bolts threadablysecured to body portion 51 so that the apertured tricolcred electrodemember 21 is securely fastened between the body portion and face plateportion 51 and 53, respectively, of supporting frame 41 in a drumhead orstretched membrane fashion. If desired, certain portions of the faceplate 53 may be hollowed out as at 57 in order to form a pocket forreceiving the ends of the spacer elements 44 upon the supporting frameand apertured electrode member 21 being supported in assembled relationwith transparent reflecting electrode member 26.

Because apertured electrode member 21 is of relatively thinconstruction, upon being stretched across the opening in supportingframe 41 in a drumhead or stretched membrane fashion, the electrodemember is highly subject to vibrations in the manner of a drumhead. Suchvibrations cannot be tolerated in the present structure, however, andtherefore any tendency of the member to vibrate must be eliminated, orat least reduced to a minimum. To accomplish this, vibration dampingmeans are provided which includes a thin, fiat, relatively wide strip58, best seen in Fig. 1 and ll, having a pair of apertures in each ofthe ends thereof. Strip 58 is mounted with the plane thereofperpendicular to the plane of electrode member 21, in order that one ofthe thin edges thereof might engage apertured electrode member 21 toprevent any tendency of the member to vibrate, and is supported in thisfashion by a pair of mounting blocks 61 secured to opposite faces of thesupporting frame 41, in the manner shown in Fig. 1 of the drawings. Asis best seen in Fig. 12 of the drawings, each of the supporting blocks61 has a slot 62 extending transverse to its length for receiving theend of strip 58, and intercepting a substantially U-shaped groove 65 inthe face thereof opposite the slot at substantially a right angle. Themounting blocks 61 are supported on supporting frame 41 with the faceshaving U-shaped grooves 65 formed therein, engaging the surface of thesupporting frame, and have a pair of wire springs 59 supported therein.The wire springs are secured in the apertures in the ends of the strip58 with their respective ends coacting with a cam surface defined in themounting blocks by U-shaped grooves 65 to place the strip 58 undertension. By this construction, the strip 58 is maintained under tensionwith one of the thin edges thereof adjacent to the surface of theelectrode member 21, and with the plane thereof at substantially rightangles with respect to the plane of electrode member 21. In order toassure against vibration of the electrode member, it is desirable thatthe edge of strip 58 adjacent apertured electrode member 21 be solderedto the electrode member, as shown in Fig. l, at one or more points 66along its length. To accomplish this, it is necessary to use a solder,such as indium, which has a relatively low melting point. Thisrequirement is impressed with regard to the solder used, due to the factthat during the bake out portion of the tube sealing operation, the thinelectrode member 21 will be caused to expand. Should the solder 66become set while the electrode member is still in expanded condition, itcan be appreciated that crippling or warping of the electrode memberwould occur. Consequently, a low melting point solder is used to securethe edge of strip 58 to the electrode member, which will remain in themolten state until the electrode member has contracted after bake out"to its normal size. 7

Adverting again to Fig. 4 of the drawings, it can be seen that theapertures 22 in the electrode member 21 17 are disposed along radiallines having a common centerpoint, andconsequently the webbing or sheetmaterial out of which electrode member 21 is constructed intermediateadjacent apertures disposed along the same arcubeam as it sweeps acrossthe apertures adjacent the strip. 7

Thus, one, two, or any number of vibration damping strips 58 may besecured on the supporting frame 41 for substantially preventingmicrophonic tendencies of the structure, without in any manner affectingelectronically the operation of the image reproducing electrodestructure.

With the apertured, tri-colored electrode member secured to supportingframe 41, and mounted in spacedapart parallel relationship withtransparent reflecting electrode member 26 in the above-describedmanner, the sub assembly reflecting type, image reproducing electrodestructure formed thereby is secured within hemispherical body portion 11of the television tube envelope. The hemispherical body portion 11 isconstructed of an electrically conductivematerial preferably chrome ironto match the expansion of the glass face portion 12, and has a pluralityof electrically conductive supports 67 secured to its inner surface by anumber of electrically conductive screws threadably attached tohemispherical body portion 11,.and having the end thereof fused so as toform an air-tight seal around the opening receiving the screw.

Each of the conductive supports 67 has the surface there of engaginghemispherical body portion 11 complementarily shaped to fitithe surfaceof the hemispherical body portion, and has a plurality of internallythreaded bolt holes in one end thereof for receiving bolts adapted topass through a particular one of a plurality of projecting cars 68, 69and 71, integral with the face plate portion 53 of supporting frame 41,for securing the supporting frame 41 within hemispherical body portion11. In this manner, the apertured, tri-colored electrode struc tuer isrigidly secured within the tube envelope in a position such that thepoint source 19 of the electron beam is located with respect to theplane apertured tri-colored electrode member 21 in the mannerillustrated in'Fig. 3 of the drawings. Further, by reason of the aboveconstruction, the operating potential V can be supplied to electrodemember 21 by connecting the conductive hemispherical body portion ll tothe source of potential V0. In order to supply the potential Vc totransparent reflecting electrode member 26, a cup-shaped insulatingmember 72 (best seen in Fig. 1) is secured to the hemispherical bodyportion 11 of the tube, which is centrally apertured, and has aconductive post 73 extending therethrough, to which the resilientcontact arm 47, described in connection with Fig. 9, is electricallyconnected. The cup-shaped insulating member 72 is secured tohemispherical body portion 11 with an air-tight connection, and forms anthe tight seal around the conductive post 73. Likewise, the conical neckportion 13, and the transparent face portion 12 of the tube are securedto hemispherical body portion 11 with air-tight connections. If desired,transparent face portion 12 may be connected to hemispherical bodyportion 11 through the medium of a point welded flanged joint, indicatedat 74, in order to facilitate manufacture of the tube.

Operation of new and improved reflecting type tri-color tube Thesynchronizing com-' ponents of the received television signal aresupplied to 18 the vertical deflection means 17, and to the horizontaldeflection means 18, both of which may be of either of theelectromagnetic type or the electrostatic type, and cause the electronbeam to vertically and horizontally scan the tri-color apertured imagereproducing electrode member 21 along substantially straight lines, in awellknown manner. Simultaneously, color synchronizing signals aresupplied to either the transparent reflecting electrode member 22, oralternatively, to apertured tri-color electrode member 21. Thus, as theelectron beam scans back and forth across the apertured electrode member21 in tracing out an image to be reproduced, it passes through theapertures 22 in the member, is reversed through the action of theretarding field existing between the two electrode members, and impingesupon a particular colored phosphorescent material. The phosphorescentmaterial that the electron beam impinges upon of course determines thecolor excited in that particular portion of the reproduced image, and istherefore varied by the color synchronizing signals. Hence, the tube maybe used to reproduce a color television picture from a received coloredtelevision signal which supplies, in addition to the' video signal andthe usualline and frame synchronizing signals, a color synchronizingsignal. The tube may be used with either a dot sequential, a linesequentiai, a frame sequential, or a simultaneous colored televisionsystem; but, in the case of the simultaneous colored television system,however, the received simultaneous color information must be firstchanged to colored synchronizing signals which can be employedsequentially to operate the tube.

From the foregoing description,.it can be readily appreciated that theinvention provides a new and improved, reflection type, tri-color, imagereproducing television tube for use in a colored television receivingsystem, which is relatively simple and cheap to construct, and whichdoes not require the use of complicated and expensive circuitry, or tubestructure, in order to achieve activation of desired color sequences.The inventional also provides an improved method and means forsupporting in spacedapart relation two elements or electrode members ofan image reproducing tube, which are maintained at diiferent electricpotentials, in a manner such that arcing is prevented. Further, theinvention provides an improved supporting frame construction for theelectrode member of a cathode-ray image reproducing tube which includesvibration damping means for reducing to a minimum any tendency of theelectrode member to vibrate. In addition to the above, the inventionalso provides a new and improved method for forming apertures in arelatively thin sheet material in a manner such that the aperturedmember produced thereby is particularly well suited for use as anelectrode member of a cathode-ray image reproducing tube by reason ofthe fact that the members thus produced have little shading effect onthe intensity of an electron beam passing through the apertures therein.Additionally, the invention makes available a reflecting type tri-colorreproducing tube having ail of the above desirable characteristicsembodied in a single article.

In the light of the above teachings, it is obvious that othermodifications and variations of the invention will be suggested to thoseskilled in the art. It is therefore to be understood that changes may bemade herein which are within the full intended scope of the invention,as defined by the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An image reproducing electrode structure for a cathode ray tubecomprising a first electrically conductive image reproducing electrodemember having a prearranged design of different color phosphorescentmaterials secured thereto and maintained at a predetermined electricpotential, a second electrically conductive planar member spaced fromand substantially parallel to said first member and maintained at anelectric potential dif' ferent from the electric potential of said firstmember, a plurality of electrically conductive hydrogen surface treatedglass spacer elements having a relatively high resistivity to the flowof electric current and disposed about said members for spacing the sameapart, and means for holding said members and said spacer elements inassembled relation.

2. A cathode ray image reproducing tube including an outer envelope, animage reproducing electrode structure supported Within said envelope,said electrode structure comprising a first apertured electricallyconductive image reproducing planar electrode member having a pluralityof concentrically arranged dilferent color emitting arcuate rows ofphosphorescent material secured thereto, and maintained at apredetermined electric potential, a second transparent electricallyconductive reflecting electrode member spaced from and parallel to saidfirst member and maintained at an electric potential different from theelectric potential of said first member, said first and second membersbeing spaced apart by a plurality of circumferentially spaced spacerelements of insulating material having a treated surface providing arelatively high resistivity conductive coating for establishing auniform voltage gradient between said electrodes, and an electron gunsupported within said envelope in a position relative to said firstapertured member such that the electrons produced thereby pass throughthe apertures in said first member are reflected by said second memberand impinge along any selected one of the different colored rows ofphosphorescent material on said first member at equal angles ofincidence.

3. A cathode ray image reproducing tube including an outer envelope, animage reproducing electrode structure supported within said envelope,said electrode structure comprising a first apertured, electricallyconductive image reproducing planar electrode member having a pluralityof concentrically and symmetrically arranged different color emittingcontinuous arcuate lines of phosphorescent material secured thereto, andmaintained at a predetermined electric potential, a second transparentelectrically conductive reflecting electrode member spaced from andparallel to said first member and maintained at an electric potentialdifferent from the electric potential of said first member, said firstand second members being spaced apart by a plurality ofcircumferentially spaced spacer elements of insulating material having3. treated surface having a relatively high resistivity conductivecoating for establishing a uniform voltage gradient between saidelectrodes, and an electron gun supported within said envelope in aposition relative to said apertured electrode member such that theelectrons produced thereby pass through the apertures in said member,are reflected by said second member, and impinge upon said firstelectrode member at equal angles of incidence along any desired colorline of phosphorescent material.

4. A cathode ray image reproducing tube including an outer envelope, animage reproducing electrode structure supported Within said envelope,said electrode structure comprising a first electrically conductiveplanar electrode member maintained ata predetermined electric potential,said first electrode member having a plurality of concentricallyarranged arcuate rows of spaced apart apertures therein, and a pluralityof concentrically and symmetrically arranged different colored arcuaterows of phosphorescent material secured thereto intermediate said rowsof apertures, the position of said concentric rows of apertures anddifferent color emitting rows of phosphorescent material beingestablished by varying length radii having the same center point androtated through respective angular distances determined by thedimensions of the image reproducing area of the member, a secondtransparent electrically conductive planar reflecting electrode memberspaced from and parallel to said first member and maintained at anelectric potential different from-the electric potential of said firstmember, said first and second memspaced glass spacer elements having atreated surface to provide a relatively high resistivity conductivecoating to provide a uniform voltage gradient between said electrodes,and an electron gun supported Within said envelope in a position along aline perpendicular to the plane containing said first electrode memberand passing through the common center point of the concentricallyarranged, arcuate rows of apertures and phosphorescent material and onthe side thereof opposite said second reflecting electrode memberwhereby the electrons produced thereby pass through said first electrodemember, are reflected by said second reflecting electrode member, andselectively impinge upon said first electrode member at equal angles ofincidence along any selected one of said different coloredconcentrically arranged lines of phosphorescent material.

5. An electrode structure for a cathode ray tube comprising a supportingframe, a relatively thin planar conductive electrode member adapted tobe disposed in the electron beam of a cathode ray tube and having theouter edges thereof secured to said frame in a drumhead fashion, andvibration damping means cooperating with said relatively thin electrodemember to reduce vibrations thereof, said damping means comprising atleast one thin flat relatively wide strip having the ends thereofsecured between portions of said frame with one of the thin edgesthereof positioned adjacent to and engaging one of the surfaces of saidrelatively thin member at, at least one point along the length thereofwith the plane of said strip at substantially a right angle with respectto the plane of said member.

6. An image reproducing electrode for a cathode ray tube comprising asupporting frame, a relatively thin planar conductive member adapted tobe disposed in the electron beam of a cathode ray tube and having theouter edges thereof secured to said frame in a dmmhead fashion, andvibration damping means cooperating with said rela tively thin member toreduce vibrations thereof, said damping means comprising at least onethin flat relatively Wide strip having the ends thereof secured betweenportions of said frame, and spring biasing means enacting with the endsof said strip and-said frame for maintaining one of the thin edges ofsaid strip adjacent to and ber at, at least one point along the lengththereof with the plane of said strip at substantially a right angle withrespect to the plane of said member.

7. An image reproducing electrode for a cathode ray tube comprising asupporting frame, a relatively thin planar conductive member adapted tobe disposed in the electron beam of a cathode ray tube and having theouter edges thereof secured to said frame in a drumhead fashion, andvibration damping means cooperating with said relatively thin member toreduce vibrations thereof, said damping means comprising at least onethin flat relatively Wide strip having apertures formed in each of theends thereof, a pair of mounting blocks secured to oppositeportions ofsaid frame, said mounting blocks having slots in the adjacent facesthereof for receiving the ends of said strip and grooves formed in thefaces thereof opposite said slotted faces, said grooves defining a camsurface, and wire springs supported in the apertures in the ends of saidstrip and coacting with the cam surface in said blocks for maintainingsaid strip under tension with one of the thin edges thereof adjacent toone of the surfaces of said relatively thin electrode member and theplane of said strip at substantially a right angle with respect to theplane of said member, the edge of said strip adjacent said thin memberbeing soldered to said thin member at, at least one point along thelength of said strip.

8. A cathode ray image reproducing tube including an envelope, anelectrode supported within said envelope,

said electrode comprising a supporting frame, a relatively thin planarconductive member having the outer edges thereof secured to said framein a drumhead fashion, and vibration damping means cooperating with saidrelatively thin member to reduce vibrations thereof, said damping meanscomprising at least one thin flat relatively wide strip having the endsthereof secured between portions of said frame with one of the thinedges thereof adjacent to and engaging one of the surfaces of saidrelatively thin member at, at least one point along the length thereofwith the plane of said strip at substantially a right angle with respectto the plane of said member, and an electron gun supported in saidenvelope for producing an electron beam adapted to be swept across saidrelatively thin member in tracing out an image reproduction.

9. A cathode ray image reproducing tube including an outer envelope, animage reproducing electrode structure supported within said envelope,said electrode structure comprising a first electrically conductive thinplanar electrode member maintained at a predetermined electric tinuousarcuate linesof phosphorescent material secured thereto intermediatesaid rows of apertures, the position of said concentric rows ofapertures and lines of difierent color rows of phosphorescent materialbeing established by varying length radii having the same center pointand rotated through respective angular distances determined by thedimensions of the image reproducing area of the member, desired ones ofsaid apertures being formed by the juncture of corresponding boresetched in opposite sides of said thin electrode member, saidcorresponding bores being offset a predetermined amount in apredetermined direction whereby the edges of the membr defining theapertures form some predetermined angle with respect to the surface ofthe member, a second transparent electrically conductive planarreflecting electrode member spaced from and parallel to said firstmember and maintained at an electric potential difierent from theelectric potential of said first member, said first and second membersbeing spaced apart by a plurality of circumferentially spaced glassspacer elements having a treated surface to provide a conductive coatinghaving a relatively high resistivity to the flow of electric currentwhereby the potential gradient between said members is maintained at adesired level and is evenly distributed over the length of said spacerelements, and an electron gun supported within said envelope in aposition along a line perpendicular to the plane containing said firstelectrode member and passing through the common center point of theconcentrically arranged, arcuate rows of apertures and phosphorescentmaterial and on the side thereof opposite said second reflectingelectrode member whereby the electrons produced thereby pass throughsaid first electrode member, are reflected by said second reflectingelectrode member, and selectively impinge upon said first electrodemember at equal angles of incidence along any selected one of saiddifferent colored concentrically arranged lines of phosphorescentmaterial, the direction and amount of offset of each of saidcorresponding pairs of bores forming apertures in said first electrodemember being determined by the relative location of the aperture formedby the bores with respect to the electron gun whereby thecross-sectional area of each aperture is a maximum along a substantiallystraight line defining the path of the electrons emitted by the electrongun and passing through the aperture.

10. The method of constructing apertures in a relatively thin cathoderay tube electrode member with the edges of the member defining theapertures describing predetermined angles with respect to the surface ofthe member, said method comprising forming a set of first bores in onemajor surface of said relatively thin member extending into said memberin the direction of the thin dimension thereof, forming a set of secondbores in the opposite major surface of the relatively thin memberextending into the relatively thin member in the direction of the thindimension thereof, offsetting each one of said second bores during theformation thereof a predetermined amount along a major dimension from acorresponding first bore, and subjecting the member to the formingaction for a sulficient period of time to allow said first and secondbores to extend through the thickness of the thin member a sufficientdistance to join together and form an aperture passing entirely throughthe thickness of the relatively thin member in a manner such that theedges of the member defining the aperture describe an angle relative tothe surface of the member, the angle being determined by the amount anddirection of offset between corresponding first and second bores.

References Cited in the file of this patent UNITED STATES PATENTS393,867 Tompsett Dec. 4, 1888 2,063,610 Linsell Dec. 8, 1936 2,123,636Schwartz July 12, 1938 2,182,578 Blumlein et a1. Dec. 5, 1939 2,250,528Gray July 29, 1941 2,466,440 Swedlund Aug. 3, 1948 2,512,655 Kohler June27, 1950 2,532,339 Schlesinger Dec. 5, 1950 2,543,046 Murray Feb. 27,1951 2,577,038 Rose Dec. 4, 1951 2,590,764 Forgue Mar. 25, 19522,606,303 Bramley Aug. 5, 1952 2,611,100 Faulkner et al Sept. 16, 19522,615,087 Rines Oct. 21, 1952 2,635,205 Olson Apr. 14, 1953 2,663,821Law Dec. 22, 1953 2,728,025 Weimer Dec. 20, 1955 OTHER REFERENCES RCAReview, September 1951, volume XII, Number 3, Part II, pages 503-512.

